new project of long term sustained spherical tokamak in ... file3rd iaea tm on st and 11th int. ws...

3rd IAEA TM on ST and 11th Int. WS on ST2005.10.3-6 / St. Petersburg

Invited Oral

New Project of Long Term Sustained Spherical Tokamak in Kyushu University

＜＜ Abstract ＞＞A new project of long term sustained spherical tokamak in Kyushu University has been proposed and

the device construction has been started as the first year of three years plan (2005-2007) .Main objectives of the project are to investigate the following issues:

i) Development of current start-up and super-long-term current driving in a spherical tokamakii) Integrated studies of plasma performance and recycling of super-long-term sustained spherical

tokamak with the advanced PWI handling by active wall-temperature controlling and a divertor systemwith intensive pumping.

The device parameters are decided to be as a major radius of R = 0.64 m, a minor radius of a = 0.36 m, and a magnetic field strength of B = 0.25 T in order to carry out the issues above. A plasma current of 100 kA with the density of 0.4 x 1019 m–3 at a heating power level of 1 MW is expected to be obtained in the quasi-steady state operation

Presented by Kohnosuke SATO K.N. Sato, H. Zushi, K. Hanada, K. Nakamura, M. Sakamoto, H. Idei, M. Hasegawa,

S. Kawasaki, H. Nakashima, A. Higashijima, N. Yoshida; K. Tokunaga, All Japan ST Research Group*, M. Peng** (Device Review Committee#

Advanced Fusion Research Center, RIAM (Research Institute for Applied Mechanics), Kyushu Univ., Kasuga, Fukuoka, Japan* Univ. of Tokyo, Kyoto Univ., Hyogo Univ., Niigata Univ., Hiroshima Univ., Kyushu Tokai Univ., NIFS, JAERI

Presented by Kohnosuke SATO

H. Zushi, K. Hanada, K. Nakamura, M. Sakamoto, H. Idei, M. Hasegawa, S. Kawasaki, H. Nakashima, A. Higashijima, N. Yoshida; K. Tokunaga,

All Japan ST Research Group* (In the framework of Bi-Directional Collaboration Res. System at NIFS)M. Peng** (Device Review Committee# under the framework of Bi-Directional Collaboration Res. Committee at NIFS)

*#Y. Takase, Y. Ono, Y. Ogawa, K.N. Sato, H. Zushi, K. Hanada, N. Yoshida, Y. Kishimoto, T. Maekawa, M. Nagata, A. Ishida, N. Nishino, O. Mitarai, A. Komori, Y. Nagayama,

T. Hayashi, N. Asakura, M. Matsukawa, S. Nishio

Advanced Fusion Research Center, RIAM (Research Institute for Applied Mechanics),Kyushu Univ., Kasuga, Fukuoka, 816-8580 Japan

*# Univ. of Tokyo, Kyoto Univ., Hyogo Univ., Niigata Univ., Hiroshima Univ., Kyushu Univ., Kyushu Tokai Univ., NIFS, JAERI

** PPPL, USA

Collaborators

＜＜ Abstract ＞＞

A new project of long term sustained spherical tokamak (ST) in Kyushu University has been proposed and approved recently. The device construction has just been started as the first year of three years plan(2005-2007 fiscal year).

Main objectives of the project are to investigate the following issues:

i ) Development of current start-up and long-term current drive in an ST,ii) Integrated studies of plasma performance and recycling of super-

long-pulse ST with the advanced PWI handling by active wall-temperature control and a divertor system with intensive pumping.

The device parameters are decided to be as a major radius of R = 0.64 m, a minor radius of a = 0.36 m, and a magnetic field strength of B = 0.25 T in order to carry out the issues above. A plasma current of 100 kA with the density of 0.4 x 1019 m–3 at a heating power level of 1 MW is expected to be obtained in the quasi-steady state operation.

＜＜ Talk Outline ＞＞

＊Recent Results in TRIAM-1MSuper Long Term Sustainment : 5 hours 16 min.

DischargeGlobal Wall Recycling⇒ Importance of PWI especially in SSO

＊New ST Project in Kyushu UniversityBackground, Purpose and FeaturesDevice Size and Various ParametersImportance of Current Drive in ST and PWI Studies

＊Summary

Plasma

SuperconductingTF Coil

PF Coils

ValveUnit

LHe Reservoir Tank

Pumping duct

CSCoil

Plasma

SuperconductingTF Coil

PF Coils

ValveUnit

LHe Reservoir Tank

Pumping duct

CSCoil

Plasma

SuperconductingTF CoilSuperconductingTF Coil

PF CoilsPF Coils

ValveUnitValveUnit

LHe Reservoir TankLHe Reservoir TankLHe Reservoir Tank

Pumping ductPumping ductPumping duct

CSCoilCSCoil

Bird’s-eye view of TRIAM-1M

8 T (Steady State)Toroidal field

0.12 mMinor radius

0.84 mMajor radius

TF coils : Nb3Sn (superconductor)PF coils : Cu (normal conductor)

Plasma facing components: High ZVacuum vessel : Stainless steelLimiter : MolybdenumDivertor : Molybdenum

◆ W/O low Z material and coating

Bird’s-Eye View and Device Features of TRIAM-1MTRIAM, Advanced Fusion Research Center

TRIAM, Advanced Fusion Research Center

In TRIAM-1M, the study and development of the long pulse operation have actively been carried out.

Particle control is one of the key issues for long pulse operation.

2.45 GHz LHCD, Limiter configuration

Progress of Long Term Tokamak Operation with TRIAM-1M





＊Summary

Poloidal Limiter（Molybdenum）

Vacuum Vessel(Stainless Steel)

Divertor plate（Molybdenum）

Without low Z material and coating

CL

Side View Top View

Plasma R = 0.8

4 m

Poloidal Limiter（Molybdenum）

Minor radius : 0.12m x 0.18m

Movable Limiter（Molybdenum）

All of the PFM are Made of High Z MaterialsTRIAM, Advanced Fusion Research Center

ScaleGlobal particle balance2 m

20 cm

2cm

20 nm

Local heat load

Transport of impurity

Radiation damageSputtering

Dust particles

Structure of depositHydrogen absorption

Local recycling

Transport of neutral particle

2 nm

Re-deposition

WallDeposition >10 nm

Hdust

Vacuum chamber

Plasma

Toroidal direction

Rad

ial d

irec

tion

Co-deposition


Hdust

Vacuum chamber

Plasma

Toroidal direction

Rad

ial d

irec

tion


Hdust


Hdust


Hdust


Hdust

Vacuum chamber

Plasma

Toroidal direction

Rad

ial d

irec

tion

Vacuum chamber

Plasma

Toroidal direction

Rad

ial d

irec

tion

Co-deposition

Multi-Scale of Plasma-Wall InteractionTRIAM, Advanced Fusion Research Center

In the main chamber

dNp / dt + dN0 / dt = Γfuel – Γpump – Γwall

Γfuel : fueling rate, Γpump : pumping rate, Γwall : net wall pumping rate

Γwall = Γab - Γre

Positive : SinkNegative : Source

wall

Reflection

Γab

Γre

Plasma

Plasma

wall

Γfuel

Γwall

ΓpumpNp

N0


Γab: hydrogen absorption

Γre: hydrogen re-emission

Global Particle Balance in the Main Chamber

0 50 100 150 200Time (min)

t ~ 30 min Plasma density increased spontaneously.Fueling was feedback-controlled to be stopped.Density was maintained only by recycling hydrogen.

Γwall < 0Γwall > 0 (sink)

(source)

-0.1

0

0.1

0.2

0.3

0.4

0 50 100 150 200

Wal

l Inv

ento

ry (1

021 H

)

Time (min)

76675

Γwall ~ 2.4x1016

H m-2 s-1

Γwall ~ - 8x1015 H m-2 s-1

Transition of Wall Role from Sink to Source in 3-Hours Discharge without ML


0 1 2 3 4 5 6Time (h)

I Hα

(a.u

.)T

(o C)

Ip (k

A)

I OII

(a.u

.)I M

oI(a

.u.)

Γfu

el(H

/s)

(a)

(b)

(c)

(d)

(e)

(f)

0 1 2 3 4 5 6Time (h)

I Hα

(a.u

.)T

(o C)

Ip (k

A)

I OII

(a.u

.)I M

oI(a

.u.)

Γfu

el(H

/s)

(a)

(b)

(c)

(d)

(e)

(f)

5 h 16 min

Γwall ~ 8.6x1016 H m-2 s-1

Continuous Wall Pumping in 5-Hours Discharge with ML


-0.1

0

0.1

0.2

0.3

0.4

Wal

l Inv

ento

ry (1

021 H

)

76675

0

50

100

150

0 1 2 3 4

Tem

pera

ture

(o C)

76675

Time (h)

0

50

100

150

0 1 2 3 4 5 6

Tem

pera

ture

(o C)

80103

Time (h)

0

2

4

6

8

10

Wal

l Inv

ento

ry (1

021 H

)

0

1

2

3

4

5

6

Wal

l Inv

ento

ry (1

020 a

tom

s)

76675, 80103

0

20

40

60

80

100

0 400 800 1200 1600

Tem

pera

ture

(o C)

Time (s)

maxwallT ～120℃

maxwallT ～55℃ Comparison

ΔT

ΔWI

Wall Inventory Wall Inventory

Wall temperatureWall temperature

τD ~ 3 h 10 min τD ~ 5 h 16 min

Γwall ~ 2.4x1016

H m-2 s-1

Γwall ~ - 8x1015 H m-2 s-1 Γwall ~ 8.6x1016 H m-2 s-1

Impact of Wall Temperature on Global Wall Pumping


Mo limiter

After M. Miyamoto, et al., J. Nucl. Mater. 337-339 (2005) 436.

Probe head

Plasma facing side Electron drift side

P-sideE-sideP-sideE-side

Thickness of deposition (RBS)2.45 LHCD (τD ~ 72min)

0

10

20

30

0

5

10

15

5 10 15 20

Mo

thic

knes

s [n

m]

Num

ber of Mo atom

s [/m2]

Distance from the Limiter Surface [mm]

x1020

P-side E-side6.4x1016 (Mo/m2s) 3.9x1017 (Mo/m2s)

Deposition rate

Surface probe

Mo Deposition in SOLTRIAM, Advanced Fusion Research Center

Background Level1

1.2

1.4

1.6

1.8

2

0 10 20 30

0 5 10 15

Num

ber o

f H a

tom

s [x

1020

/m2 ]

Mo thickness [nm]

Number of Mo atoms [x1020/m2]

E-sideP-sideunirra.

E-sideP-sideunirra.

Two kind of valuesFor thin deposition: H/Mo ~ 0.10For thick deposition: H/Mo ~ 0.04

Concentrations of H/Mo

The wall pumping rateP-side: ~6.4 x 1015 [H/m2s]E-side: ~1.3 x 1016 [H/m2s]

Contribution to the wall pumping

After M. Miyamoto, et al., J. Nucl. Mater. 337-339 (2005) 436.

Hydrogen Absorption Rate into Mo DepositTRIAM, Advanced Fusion Research Center

Macroscopic method[Particle balance]

Dynamic retention

Wall pumping rate~2.4 x 1016 (H/m2s)

Retention rate~1.3 x 1016 (H/m2s)

Surface probeERD: Elastic Recoil Detection

Microscopic methods

Static retention


Good Agreement of Wall Pumping Rate by Macroscopic and Microscopic Methods

＊概要：プラズマ対向壁材の熱負荷分布、粒子供給率、金属不純物の入射束と再堆積などの実時間計測や解析が進んできており、長時間放電の技術開発に加えて、理学的研究の展開が進展を始めている。なお最近、周波数2.45GHzの低域混成波電流駆動により、駆動電流16 kA、密度～1x1012 cm-3のプラズマを、5時間16分間定常的に維持することに成功した。

2003.112001.91995.61990.5

1989.121988.6

• Ｈα光透過計測#80103

・再堆積のその場計測

#80103

レーザ光反射計測

Recent Results

Ｈα

・Gas fueling is controlled (by piezo-valve) so as for Ha light to be constant.

・It occurs in the discharge period after 3 hours that the piezo-valve automatically close (no gas feeding) during several tens of seconds intermittently.

・This means the particle balance is kept constant only by the wall fueling in the latter half of super long term discharge.

Plasma Current

Accumulation of Exp. Results on Long Term Sustained Plasmas--- Achievement and Understanding of Super Long Duration Discharge ---

Piezo-Valve Voltage


・Achievement of 5 hours 16 min. dis.

(B = 6T, Prf ~ 12kW, ne ~ 1 x 1012 cm-3)

・Gas fueling is controlled (by piezo-valve) so as for Hα light to be constant.

・It occurs in the discharge period after 3 hours that the piezo-valve automatically close (no gas feeding) during several tens of seconds intermittently.

・This means the particle balance is kept constant only by the wall fueling in the latter half of super long term discharge.

Influx Constant Operation

Plasma current

Hα

Piezo-valve voltage

Key issue for the achievement of super long term discharge is that high power could be injected keeping the wall temperature to be low by using a movable limiter with high heat removal capability.


Accumulation of Exp. Results on Long Term Sustained Plasmas--- Achievement and Understanding of Super Long Duration Discharge ---

• A wall plays a significant role of particle sinkand source

• Adsorption by “co-deposition” is infinite• Control of wall pumping and emission of particles

are quite difficult

• Recycling rate to be unity by “High Temperature Wall”

• Necessity of high heat load study

Proposed Steady State Particle Control in New ST Device






＊Summary

『 FUTURE DIRECTION OF NATIONAL FUSION RESEARCH （Report）』• Working Group on Fusion Research, Special Committee on Basic Issues, Subdivision on Science, Council for Science and

Technology (January 8, 2003)

３．Fusion Research Centralization Plan(5) Rearrangement and Integration of Existing Devices

Based on the decisions on centralized programs and evaluation of the existing devices, the future strategy is summarized as follows:

①As the bases of centralized programs, JT-60 and GEKKO-XII should continue operation until the start of their respective follow-on projects, and should complete their programs at the construction of the new devices.

②LHD should continue studies towards its initial research goal of achieving a universal understanding of toroidal plasmas by producing high-performance plasmas and by clarifying academic contributions to toroidal systems including ITER as an existing research program.

③ Except the three centralized devices, JT-60, GEKKO-XII, and LHD, the remaining existing devices should complete their programs at their appropriate times. However, any extension proposal associated with a novel research evolution can be a candidate for new research possibilities.

④In addition to stimulation of joint research using the four centralized programs, it is necessary to construct a research framework that provides challenging opportunities to test original ideas.

Background : Procedure and the Way of Thinking for the Future Plan (1)

③Except the three centralized devices, JT-60, GEKKO-XII, and LHD, the remaining existing de-vices should complete their programs at their appropriate times. However, any extension proposal associated with a novel research evolution can be a candidate for new research possibilities.

- 2

Based on this “Report” : 『 FUTURE DIRECTION OF NATIONAL FUSION RESEARCH （Report）』

Working Group on Fusion Research, Special Committee on Basic Issues, Subdivision on Science, Council for Science and Technology (January 8, 2003)

We have decided(1) To shut down TRIAM-1M activity,

(2) To start a new project of long term sustained spherical tokamak (ST) in Kyushu University. It has been proposed and approved recently. The device construction has just been started as the first year of three years plan (2005-2007 fiscal year). Main objectives of the project are to investigate the following issues:

i) Development of current start-up and long-term current drive in an ST,ii) Integrated studies of plasma performance and recycling of super-

long-pulse ST with the advanced PWI handling by active wall-temperature control and a divertor system with intensive pumping.

＊Purposes(1) Long Term / Steady-State Sustainment of Tight Aspect Ratio Tokamak (Spherical Tokamak)

EBW, NBI, LHCD (low density), CHI, etc.

(2) Investigation on Physics & Engineering of Long TermSustained ST Plasma （Plasma-Wall Interaction）

(not in the region of the order of L/R-time, but in the regionof much more long duration)

(3) Comprehensive Understanding of Toroidal Plasmas with LHD （in Steady State Plasmas）

Purposes and Particularities of the Project

1 0-3

1 0-2

1 0-1

10 0

10 1

1 0-2 10 -1 1 00 10 1 1 02 103 10 4 1 05

BDFH

Ip(M

A)

T im e(s)

L A T E

T S T -2T R A IM -1M

N S T X

Research Region of the Present Existing Device

Time (s)

LATE(Japan)

TST-2(Japan)

NSTX / MAST

- 7 -

1 0-3

1 0-2

1 0-1

10 0

10 1

1 0-2 10 -1 1 00 10 1 1 02 103 10 4 1 05

BDFH

Ip(M

A)

T im e(s)

L A T E

T S T -2T R A IM -1M

N S T X

Research Region of the Proposed Device

Time (s)

LATE

TST-2

NSTX / MAST

Proposed Device

Proposed Device

- 7 -

TST-2(Japan)

LATE(Japan)





＊Summary

0.6

0.5

0.4

0.3

0.2

Min

or R

adiu

s (m

)

1.00.80.60.40.2

Major Radius (m)

A=1.4

β=10%

q95=4

β=5%

A=1.2

q95=3

IP=0.3MABT=0.25TPinj=3MWn20=0.3κ=2.55δ=0.68

frad=40%

frad=50%

Purpose in the 2nd Period

• Plasma current １００ｋＡCW• β-value １０％１ sec

(Choice of device size relevant to the 2nd period purpose)

Choice of the Device SizeTRIAM, Advanced Fusion Research Center

0.45

（定常）（パルス）大半径R(m )小半径a(m )アスペクト比

真空容器半径(m )真空容器高さ(m )

BT(T) 0.25 0.25 0.5 0.25IP(M A) 0.02-0.03 0.1 0.3 0.5Pinj(M W ) 1 1 3 3

k 2.5 2.5 2.5 2.5d 0.7 0.7 0.7 0.7

<ne20>(m -3) - 0.04 0.3 0.3<Te>(keV) - 0.32 0.33 0.54<Ti>(keV) - 0.32 0.33 0.54τE(m s) - 2.5 6.8 10.8

β(%) - 1.6 13 21

βN - 1.5 3.9 3.8

βp - 0.33 0.29 0.17

q95 - 25 8.2 5ΓH (M W /m 2) - 6.5 10.1 13.6

Frad(%) 20 40 40

ΓP (Pa m 3/s) - 17.5 50 31.1

fG W - 0.16 0.41 0.24

IBS(M A) - 0.008 0.022 0.021

ηC D1019(A/W /m 2) - 0.026 0.19 0.32

0.640.361.781.42.8

第１期最終目標第２期

Typical examples of SN and DN configurations

Summary of the Device ParametersTRIAM, Advanced Fusion Research Center

10

0

1

R (m)

a (m)

NSTX/MAST

LATE

Comparison of Device SizeAdvanced Fusion Research Center

TST-2 / TS-3/4“QUEST”

QUEST : Q-shu University Experiment on Steady State Spherical Tokamak





＊Summary

Candidates

• RF current drive (LATE, TST-2)• NB current drive• Bootstrap current • Plasma merging (TS-3,4)• Helicity injection (HIST)• New concepts

Method of Current Drive in STTRIAM, Advanced Fusion Research Center

• EBW CD in ST has the potential to attain the high current drive efficiency comparable to ECCD on conventional tokamaks.

• Even in ST, wave propagation of EBW has no limitations such as cut-off.

• The experimental studies are carried out on LATE and TST-2.

• 100kA at 60 GHz 600kW on COMPASS-D

• 8.1kA at 2.45 GHz 35kW, and12.1kA at 5 GHz 130kW on LATE

• 4 kA at 8.2GHz 170 kW on TST-2• 1.2 kA at 140 GHz on W7-AS

Experimental Observations

Simulation

• 30kA at 15 GHz, 1MW on NSTX, but no optimization

EBW Current DriveTRIAM, Advanced Fusion Research Center

U. TokyoHongo~2002

U. TokyoKashiwa2004~

Kyushu U.Fukuoka

2003

TST-2

Collaboration with the Univ. of Tokyo by using TST-2(under Bi-Directional Collaboration with NIFS)


ＴＲＩＡＭ－１Ｍ

ＴＳＴ－２@K

RF Heating/CD

View of TST-2＠K (Initial Stage) with TRIAM-1MTRIAM, Advanced Fusion Research Center

During preparation of TST-2@K

ＴＳＴ－２

ＴＲＩＡＭ－１Ｍ

During preparationof TST-2@K


• A wall plays a significant role of particle sinkand source

• Adsorption by “co-deposition” is infinite• Control of wall pumping and emission of particles

are quite difficult

• Recycling rate to be unity by “High Temperature Wall”

• Necessity of high heat load study

Proposed Steady State Particle ControlTRIAM, Advanced Fusion Research Center

Vacuum Vessel ： SUS304L(< 100℃)

First Wall： W(300~500℃)

Divertor Plate： W(400~500℃)

Divertor Plate

First Wall

First Candidate

Impossible by TRIAM-1M

Actively Controlled High Temp. Wall and DivertorTRIAM, Advanced Fusion Research Center





＊Summary

Summary-1 (TRIAM-1M)

Through the studies on Super Long Pulse discharge (5 hours 16 min. and others) and PWI, a couple of quiteimportant knowledges have been obtained:

＊ Good agreement of wall pumping rate estimated by macroscopic and microscopic methods

Dynamic Retention ⇔ Static Retention

＊ Co-deposition effect plays a quite important role for wall pumping even in a metal wall device(though well recognized in carbon wall devices)


＊Purposes(1) Long Term / Steady-State Sustainment of Spherical Tokamak

EBW, NBI, LHCD (low density), CHI, etc.(2) Plasma-Wall Interaction in Spherical Tokamak

（Physics & Engineering of Long Term Sustained ST）(3) Comprehensive Understanding of Toroidal Plasmas with LHD

＊Particularities(1) Large Plasma Volume(2) High Accessibility / Flexibility ⇒ Active wall temp. control(3) Low Cost(4) Large Infrastructure for Exp.

＊ Collaboration Research Activity(1) Domestic (Bi-Directional + Inter-Univ./ Institute) Collaboration

（NIFS）（RIAM, Kyushu Univ.）(2) International Collaboration

Summary-2 ( New Project: “QUEST”- - - ST in Kyushu

University)TRIAM, Advanced Fusion Research Center

Plasma Boundary Dynamics Experimental Device, AFRC, RIAM, Kyushu University

Various Steps toward Obtaining the Consensusamong Scientists in the Universities and Institutes in Japan

Through discussion in various level as below, intense collaborations are expected to be started and performed.

(Partnership and share of roles, share of ports, diagnostics etc.)

＊TRIAM Research Meeting・１７th（1st in FY2004） - - - - 2004 April 22-23, 2004 (Starting discussion and possible collaboration on the new

device)⇒ FURKU Report 04-01、Report in JSPF [Sep. 2004]

・１８th（2nd in FY2004 ） - - - - 2004 Oct. 14-15 （Discussion on the new device） ⇒ FURKU Report 04-02・１９th（1st in FY2005 ） - - - - 2005 April 14-15 （Discus. on detailed design of the new device） ⇒ FURKU

Report 05-01・２０ｔｈ (2nd in FY2005) - - - - Planned in the end of Dec. 2005

＊Society Meeting (Japan Society of Plasma and Fusion Res., Japan Physical Society, etc)・ JSPF （Related Report Meeting, Shizuoka 2004 Nov. 23 ）

・ JSPF （Informal Meeting + Symposium, Tokyo 2005 Dec. 1 ）

＊Fusion Research Network Committee・ Report and Discussion （2004 Aug. 31, 2005 Jan. and May, etc.）

＊National Institute for Fusion Science （Bi-Directional Collaboration）（１） Steering Committee （2004 July 13, Sep. 8, etc. and 2005 June 1 = Final Decision）（２） Collaboration Committee （2004 December 8, 2005 March 8 = Final）（３） Bi-Directional Collaboration Committee （2004 July 13, October 14, 2005 Feb. 9 = Final）（４） Device Review Committee under the framework of Bi-Directional Collaboration Committee

- - - - - - １st：2004 Sep.16、２nd : Oct.6、３rd : Dec. 24, 4th : 2005 Jan. 11 = Final）


＊National Institute for Fusion Science （Bi-Directional Collaboration Research）

(1) Device Review Committee - - - (1st：2004 Sep.16、2nd :

Oct.6、3rd : Dec. 24, 4th : 2005 Jan. 11 = Final）(2) Bi-Directional Collaboration Committee

(2004 July 13, October 14, 2005 Feb. 9 = Final）(3) Collaboration Committee

（2004 December 8, 2005 March 8 = Final）(4) Steering Committee

（2004 July 13, Sep. 8, etc. and 2005 June 1 = Final Decision）

Plasma Boundary Dynamics Experimental Device, AFRC, RIAM, Kyushu University

Various Steps toward Obtaining the Consensusamong Scientists in the Universities and Institutes in Japan


＊Purposes(1) Long Term / Steady-State Sustainment of Spherical Tokamak

EBW, NBI, LHCD (low density), CHI, etc.(2) Plasma-Wall Interaction in Spherical Tokamak

（Physics & Engineering of Long Term Sustained ST）(3) Comprehensive Understanding of Toroidal Plasmas with LHD

＊Particularities(1) Large Plasma Volume(2) High Accessibility / Flexibility ⇒ Active wall temp. control(3) Low Cost(4) Large Infrastructure for Exp.

＊ Collaboration Research Activity(1) Domestic (Bi-Directional + Inter-Univ./ Institute) Collaboration

（NIFS）（RIAM, Kyushu Univ.）(2) International Collaboration

Summary-2 ( New Project: “QUEST”- - - ST in Kyushu

University)TRIAM, Advanced Fusion Research Center

new project of long term sustained spherical tokamak in ... file3rd iaea tm on st and 11th int. ws...

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